Camera RAW Color Profile Calibration: Using X-Rite ColorChecker to Create Custom DCP Camera Calibration Presets

1. The nightmare of color inconsistency across cameras in commercial photography

In commercial still life advertising, clothing e-commerce and multi-camera team shooting, the biggest pain point is the "fighting between brands' color philosophies":

1. Manufacturer’s built-in preset aesthetic bias:

• Sony Adobe's default color is more yellowish-green, Canon's skin tone is more pink, Nikon's contrast is strong, and Fuji's simulation color is thick;
• When camera A uses Sony to shoot the same model show or the same lipstick product with camera B, camera B uses Canon to shoot the same model show or the same lipstick product. The post-retoucher needs to spend dozens of hours manually adjusting the colors. Still, the colors of the two cameras cannot be completely matched, so the customer directly rejects the product.

2. DCP (DNG Camera Profile) underlying calibration logic:

• The RAW format itself does not have fixed colors, and the color profile (Profile) must map the sensor's RGB raw values to the standard CIE XYZ/Lab space.
• By shooting the international standard 24-color color card, a rigorous mathematical algorithm is used to calculate the spectral calibration color matrix of the current lens and sensor combination under the real light source on site, completely smoothing out the color differences of different camera bodies and achieving 100% physical-level color absolutely true restoration.

2. X-Rite / Calibrite 24-color standard color card shooting specifications

If the calibration photos are not taken carefully, the generated calibration files will cause serious color casts in the entire batch of photos:

1. Color card placement and light uniformity (absolutely critical):

• Place the standard 24-color color card (ColorChecker Classic/Passport) at the core of the subject;
• The color card must be strictly perpendicular to the optical axis of the camera lens (front-side light reception);
• Surface reflections and shadows are strictly prohibited: The light must be directed at the color card at a 45-degree angle. High-gloss reflections must not be allowed to appear white on the surface of the color patch. The illumination error at the left and right ends of the color card must be less than 0.1 EV.

2. Exposure and white balance are strictly controlled:

• The first grid from the left in row 4 of the color card is "Pure White (White 90% reflectance)", and the second grid is "Neutral Gray (Neutral 18%)";
• Exposure setting: The RGB brightness value of the white block on the histogram must be controlled between 230~240 (overexposure and white truncation of 255 are strictly prohibited!);
• Turn off any in-camera dynamic range expansion (such as Sony DRO, Canon highlight tone priority);
• Must shoot pure and lossless RAW format.

3. Generate Dual-Illuminant DCP calibration preset steps

The calibration file generated by a single light source can only be used for the current light; the dual light source configuration file has an automatic interpolation algorithm, which can intelligently correct the color no matter under sunlight or tungsten light:

1. Transcoding and loading:

• Import the captured RAW files containing color cards into the Adobe DNG Converter software and convert them into the universal lossless .dng format;
• Open the professional calibration software ColorChecker Camera Calibration.

2. Automatic grid alignment and feature extraction:

• Drag DNG into the software interface;
• The computer vision algorithm inside the software automatically finds 4 diagonal positioning points in the picture and accurately places sampling frames on the 24 color blocks;
• Check the sampling frame: Make sure that all sampling points fall in the center of the pure color block and do not step on the black edge plastic spacers.

3. Advanced merging of dual light sources (optional):

• Take a 5500K flash/daylight color card DNG, and then take a 2850K tungsten light/warm light color card DNG;
• Select "Dual Illuminant Profile" in the software and load the two DNGs together to generate a top-level universal calibration profile that can adapt to the color temperature of various mixed light.

4. Save configuration file:

• Name it: SonyA7IV_2470GM_Studio_Profile, and the software will automatically write it into the root directory of CameraProfiles of the Adobe system.

4. One-click application and color normalization of Lightroom/Camera Raw

1. Restart Adobe Lightroom Classic:

• Open the development module, at the "Basic $\to$ Profile" at the top of the right panel, click the four small squares on the right to browse the icon;
• Find the "User Configuration File" in the expanded directory, and the exclusive configuration you just made will appear!

2. Restore the real reality with one click:

• Click on the profile to apply:
• In an instant, the original yellowish-green skin color in the picture was automatically corrected to a healthy and transparent texture. The red product clothing accurately fell on the Pantone standard color card value. The materials shot by multiple different cameras were instantly unified into the same absolute color standard, and the commercial delivery efficiency doubled.

---